Listeriosis outbreak in Pennsylvania under investigation

Sep 20, 2002 (CIDRAP News) – Federal health officials are trying to identify the source of a listeriosis outbreak that has involved at least 26 cases, with four deaths, in Pennsylvania and neighboring states in recent weeks.

Listeria monocytogenes isolates from 26 patients have been matched by pulsed-field gel electrophoresis, pointing to a common food source, the Centers for Disease Control and Prevention (CDC) said in a Sep 18 announcement. The CDC and state health departments are testing isolates from about 50 more patients, some of which will probably match the outbreak strain, officials said. CDC spokeswoman Katie Hoskins said the source of the outbreak remained unidentified today.

All 26 patients were hospitalized, and four have died, the CDC reported. Twelve patients were from southeastern Pennsylvania, 8 from New York City, 2 from New York State, 2 from Maryland, 1 from Connecticut, and 1 from Michigan.

"The illnesses were first reported in the summer, and cases continued to be reported in September," the CDC announcement said.

Federal food safety officials last week said people in the region who are at high risk for listeriosis should take special precautions to avoid L monocytogenes infection. They said pregnant women, frail elderly people, and the immunocompromised should avoid soft cheeses, refrigerated pates or meat spreads, refrigerated smoked seafood, and unpasteurized milk, and should also avoid hot dogs and lunch meats unless they are thoroughly heated. The warning came from the Food and Drug Administration and the Agriculture Department's Food Safety and Inspection Service.

Typical early symptoms of listeriosis include fever, muscle aches, and sometimes gastrointestinal complaints. Listeriosis in pregnant women can lead to premature delivery, infection of the newborn, or stillbirth, the CDC noted.

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